Hydraulic transformer



EBEQWE 2 sheets Sheet 1 o w mm m 9 M4 0 w m H W0 2; 1H.

fli N 8 nummmw lui j u du MW d Mamgl 197 J. R. HORETZKE HYDRAULICTRANSFORMER Flled June 15, 1965 2 4 i \\\\\S\ \.4 mm a H Q8 6 2ATTORNEYS United States Patent 3,310,943 HYDRAULIC TRANSFORMER John R.Horetzke, Royal Oak, Mich., assignor to Grand Steel & Manufacturing Co.,Clawson, Mich, a corporation of Michigan Filed June 15, 1965, Ser. No.463,993 16 Claims. (Cl. 6054.5)

The invention relates to hydraulic presses and refers more specificallyto hydraulic press actuating apparatus including a single pump and ahydraulic transformer capable of moving a press toward a workpiece at ahigh velocity under low pressure during a portion of a ram stroke whilea die carried by the ram approaches the workpiece and automaticallyadjusting to move the ram at a lower velocity under higher pressure forthe remainder of the ram stroke while the workpiece is engaged and workis performed on the workpiece.

In the operation of a hydraulic ram press it is desirable to move thepress ram toward a workpiece at a more rapid rate before engagement of adie carried by the ram with the workpiece than thereafter and to providehigh pressure during performance of Work on the workpiece. Suchoperation shortens the cycle of operation for the press so that thepress is able to satisfactorily complete more workpieces in apredetermined time.

-In the past the high speed advancing of a ram toward a workpiece andsubsequent low speed, high pressure engagement of a die carried by theram with the workpiece has required relatively complicated hydraulicpress actuating apparatus including two separate pumps for efiicientcirculation of hydraulic fluid for the apparatus. Such hydraulic pressactuating apparatus has been relatively expensive and therefore limitedin use.

It is one of the objects of the present invention to provide improvedhydraulic press actuating apparatus.

Another object is to provide a hydraulic actuating apparatus forinitially moving a ram toward a workpiece at a high rate of travel undera low pressure and subsequently moving the ram into engagement with theworkpiece at a lower rate of travel and working the work piece under ahigh pressure which apparatus includes a single hydraulic fluid pump.

Another object is to provide hydraulic actuating apparatus for moving apress ram toward a workpiece at a high rate of travel under low pressureand subsequently engaging the workpiece with the ram moving at a lowerrate of travel under a high pressure including a hydraulic t-ransformer, means for pumping hydraulic fluid into the trans former at a lowrate under a high pressure to force hydraulic fluid out of thetransformer to the press ram at a high rate and low pressure while theram is approaching the workpiece and means for bypassing the hydraulictransformer to pump the hydraulic fluid at the low rate under a highpressure directly to the press ram immediately before engagement of theworkpiece and during work on the workpiece.

Another object is to provide hydraulic press actuating apparatus as setforth above and further including means for returning the ram to theraised position and for selecting a predetermined limiting raisedposition for the ram.

Another object is to provide hydraulic press actuating apparatus as setforth above wherein the apparatus is provided with means for rechargingthe hydraulic transformer on raising of the ram.

Another object is to provide hydraulic press actuating apparatus as setforth above wherein the apparatus is provided with an alternativeoverflow path from the hydraulic transformer to the hydraulic fluidreservoir for presses having stripper or knock-out structure operable onthe return stroke of the press.

3,31%,943 Patented Mar. 28, 1967 Another object is to provide animproved hydraulic transformer.

Another object is to provide hydraulic press actuating apparatus whichis simple in construction, economical to manufacture and eflicient inuse.

Other objects and features of the invention will become apparent as thedescription proceeds, especially when taken in conjunction with theaccompanying drawings, illustrating a preferred embodiment of theinvention, wherein:

FIGURE 1 is a partially broken away diagrammatic perspective view ofpress structure including hydraulic actuating apparatus having ahydraulic transformer constructed in accordance with the inventioninstalled thereon.

FIGURE 2 is a schematic hydraulic diagram of the hydraulic actuatingapparatus of the press structure illustrated in FIGURE 1.

With particular reference to the figures of the drawings, one embodimentof the present invention will now be considered in detail.

As shown in FIGURE 1, hydraulic press actuating apparatus 10 ispositioned on the press 12 to lower and raise the ram 14 of the press12. The hydraulic apparatus includes the hydraulic transformer 16connected between the pump 18 and the cylinder 20 in which the ram 14 isreciprocated.

In operation the hydraulic transformer 16 functions to pump hydraulicfluid into the top of the cylinder 20 at a hi h rate and low pressure tocause the ram 14 to descend rapidly to a predetermined position. At thepredetermined position the hydraulic apparatus 10 functions toautomatically bypass the hydraulic transformer 16 and feed the hydraulicfluid pumped by the pump 18 at a relatively low rate and high pressuredirectly into the cylinder 20 to cause the ram 14 to continue to descendat a slower speed under the higher pressure for forming a workpiece (notshown) positioned on the press 12.

More specifically the press 12 includes a base 22 supporting thehorizontal bed 24 on which a lower die or workpiece (not shown) may bepositioned beneath the ram 14. Press 12 further includes superstructure26 for supporting the ram 14, ram cylinder 20 and hydraulic apparatus10. The ram 14 and ram cylinder 20 are part of the press structure 12.

The hydraulic apparatu 10 includes the hydraulic fluid tank 28positioned in the base 22 of the press 12, pump 18, 'motor 30, hydraulictransformer 16, manually operated four-way valve 34, piloted four-wayvalve 38, switching four-way valve 40 and cam actuating structure 42therefor, upper ram limit four-way valve 44 and cam actuating structure46 therefor, foot valve 48, check valve 50, pressure relief valve 52 andpump bypass valve 54 connected as shown best in FIGURE 2. The upper ramlimit four-way valve 44 and cam operating structure 46 therefor, thepump bypass valve 54, foot valve 48 and sequencing valve 36 may beeliminated along with their corresponding function as will be seensubsequently.

The pump 18 is capable of pumping approximately fifteen gallons perminute of hydraulic fluid at a pressure of one thousand pounds persquare inch. As shown best in FIGURE 2, the pump is connected to thetank 28 through hydraulic conduit 56 and to the manually actuatedfour-way valve through the hydraulic conduit 58. The output of the pump18 is addition-ally connected to the down-stream side of the check valve50 through conduit 60 and is connected to the input side of the pumpreturn valve 54 through the conduit 62. Pump 18 may be a VickersIncorporated No. 104-D pump and is driven by motor 30 through outputshaft 64 and the dog clutch structure 66.

The four-way valve 34 may be manually actuated by handle 32. Besidesbeing connected to the output of the pump 18 through the conduit 58valve 34 is connected through conduit 68 to the input side of thesequencing valve 36. The manually actuated four-way valve 34 is furtherconnected to the input side of the foot valve 48 through conduit 70 andto the return side of the piloted four-way valve 38 by the pilot conduit72. The valve 34 may be a Vickers Incorporated No. C-430A valve which inits actuated condition, as illustrated in FIGURE 2. vents the hydraulicconduit 78 from foot valve 48 and the pilot conduit 72 from the pilotedfour-way valve 38 to the tank 28 through the conduit 74 and connects theoutput of the pump 18 to the input side of the sequencing valve 36. Inits reverse actuated condition the valve 34 vents the conduit 68 fromthe sequencing valve 36 to the tank 28 and applies hydraulic fluid atpump pressure through the foot valve 48 to the bottom of ram cylinderthrough hydraulic conduits 70 and 146 to raise the ram 14 and applieshydraulic fluid under pressure in pilot conduit 72 to reset the pilotedfour-way valve 38. Valve 34 is also provided with a neutral unactuatedposition in which all conduits connected thereto are blocked.

The sequence valve 36 includes a check valve portion 76 through whichhydraulic fluid is'passed by means of conduits 78, 80 and 82 to thehydraulic transformer 16 or through conduits 78 and 84 to the pilotedfour-way valve 38. Sequence valve 36 further includes a piloted reliefvalve portion 86 through which hydraulic fluid from the hydraulictransformer 16 may be returned to the tank 28 by way of conduits 82, 80,and 78, sequence valve 36, conduit 68, four-Way valve 34 and conduit 74should the check valve 50 fail to open due, for example, to a stripperor knock-out used with the press 12 on the return stroke of the ram 14.The sequence valve 36 may be a Vickers Incorporated No. RCT06-Al-l0.

The hydraulic transformer 16, as best shown in FIG- URE 1, includes topand bottom end plates 88 and 90 and a cylinder 92 positioned between thetop and bottom end plates 88 and 90. The hydraulic transformer furtherincludes a rod 94 secured to the bottom end plate 90 and having anopening 96 extending axially therethrough connected through the bottomend plate 90 to the conduit 82 and a piston 98 reciprocally mounted inthe cylinder 92 and having a recess 100 therein receiving the upper endof the rod 94, as shown best in FIGURE 1. Suitable sealing structure maybe provided between the upper end of the rod 94 and the recess 100 ofthe piston 98, between the outer surface of the piston 98 and thecylinder 92 and between the ends of the cylinder 92 and the top andbottom end plates 88 and 90. The top and bottom end plates 88 and 90 areheld in assembly with the cylinder 92 by means of the longitudinallyextending rods 104 which extend through the end plates 88 and 98 at thecorners of the end plates which may be held in position by bolts or thelike.

The diameter of the piston 98 is chosen to have four times the area ofthe rod 94. Thus hydraulic fluid entering the recess 100 at, forexample, a rate of fifteen gallons per minute under a pressure of onethousand pounds per square inch will cause movement of hydraulic fluidout of the top chamber 106 of the hydraulic transformer 16 to the top ofcylinder 20 through conduit 108, four-way valve 38 and conduit 110 atsixty gallons per minute at a pressure of two hundred fifty pounds persquare inch to move the ram 14 downward at a relatively fast speed, asfor example six hundred inches per minute.

Conversely, on the return stroke of the ram 14, hydraulic fluid isforced out of the upper chamber 112 of cylinder 20, back through conduit110, piloted four-way valve 38, conduit 108 and into chamber 106 of thehydraulic transformer 16. If the fluid returns to the hydraulictransformer in chamber 106 at a rate of fifteen gallons per minute, at apressure of one thousand pounds per square inch, the hydraulic fluidwill be forced out of the chamber 100 at a possible pressure of up tofour thousand pounds per square inch at the rate of three and one-fourthgallons per minute.

The piloted four-way valve 38, as indicated, is connected to thesequencing valve 36 through conduits 84 and 78 to the hydraulictransformer 16 through conduit 108 and to the ram cylinder 20 throughthe conduit 110. Four-way valve 38 has also been indicated as connectedto the pilot conduit 72. Valve 38 is additionally connected to the pilotconduit 114 through the switching four-way valve 40 and to tank 28through conduit 118. The piloted four-way valve 38 in its rightward orinitial position, as shown in FIGURE 2, connects the chamber 106 ofhydraulic transformer 16 to the chamber 112 of the ram cylinder 20. Atthis time the conduit 84 is blocked.

When the valve 38 is moved to the left on receipt of a piloting signalfrom pilot conduit 114, the chamber 112 of cylinder 20 is connecteddirectly to the sequencing valve 36 through the conduits 78 and 84 andthe conduit 108 is blocked. On receipt of a pilot signal from pilotconduit 72, the valve 38 will return to the position shown in FIGURE 2.

Thus, in accordance with the position of the piloted four-way valve 38,hydraulic fluid through valve 38 for the actuation of the ram 14 mayeither come from the hydraulic transformer 16 actuated by hydraulicfluid from the sequence valve 36 or may be fed directly from thesequence valve 36 through valve 38 to the cylinder 20. The pilotedfour-way valve may be a Vickers Incorporated No. DG354060-20.

The switching four-way valve 40 is connected to the manual four-wayvalve 34 through conduit 68 and pilot conduit 116. Valve 40 is connectedto the hydraulic fluid tank 28 through conduit 118. In the actuatedposition valve 40 connects pilot conduit 116 with pilot conduit 114 toshift the piloted four-way valve 38 to the left. In the unactuatedcondition the valve 40 closes the pilot conduit 116 and vents the pilotconduit 114 to the hydraulic fluid supply tank 28 through conduit 118.Valve 40 may be a Vickers Incorporated No. C572E valve.

The valve 40 is mechanically actuated by the cam actuating structure 42.operating in conjunction with a cam follower 120 connected to the valve40. The cam actuating structure, as shown best in FIGURE 1, is carriedon one end of a yoke 122 connected to the ram 14 and includes thevertically extending rod 124 and the cam 126 adjustably mounted on therod 124. Thus, the switching four-way valve 40 is actuated in accordancewith the vertical position of the ram 14.

The ram upper limit four-way valve 44 is connected by pilot conduit 128to the conduit 68 from four-way valve 34 and is connected by pilotconduit 130 to the bypass valve 54. Valve 44 is further connected by aconduit 132 to the hydraulic fluid tank 28. In the unactuated conditionshown, the valve 44 connects the pilot conduit 130 from bypass valve 54to the tank 28 and closes the pilot conduit 128. On actuation by the camactuating structure 46, the four-way valve 44 will provide a directconnection between the pilot conduits 128 and 130 to actuate the bypassvalve 54 and close the conduit 132.

The cam actuating structure 46 for the four-way valve 44 is secured tothe other end of the yoke 122 on the ram 14 and includes the adjustablerod 134 and actuating cam 136. Thus, the actuation of the ram upperlimit four-way valve 44 depends on the vertical position of the ram 14.

The bypass valve 54 is, as previously indicated, internally connected tothe pump 18 through conduit 62 and is connected to the pilot conduit 128through upper limit four-way valve 44 and pilot conduit 130. The bypassvalve 54 is further connected to the hydraulic fluid tank 28 through theconduit 138. On receipt of a signal from the pilot conduit 130, thebypass valve 10 is actuated to bypass the hydraulic fluid from the pump18 through the conduit 6-2 back to the tank 28 through conduit 138.

Thus, the return stroke of the ram 14 may be limited by the setting ofthe cam 136 since the valve 54 will open the bypass around the pump 18when the upper limit valve 44 is actuated by the cam 136 to connect thepilot conduits 128 and 130. The bypass valve 54 may be a VickersIncorporated No. CT06B.

The pressure relief valve 52, as shown is connected to the chamber 106of hydraulic transformer 16 by conduit 140 and is connected to thehydraulic conduit 68 through the conduit 142. The pressure relief valve52 operates to return excess fluid pumped into the hydraulic transformer16 from the chamber 112 of cylinder 20 to the tank 22 through conduits140, 142, 68 and 74 during the return stroke of the ram 14. The pressurerelief valve 52 may be a Vickers Incorporated No. C-175-B valve.

The foot valve 48 is connected to the four-way valve 34 through theconduit 70, as previously indicated, and is connected to the bottomchamber 144 of cylinder 20 by the conduit 146. The foot valve 48includes a check valve portion 148 through which hydraulic fluid ispumped into chamber 144 of cylinder 20 to provide the return stroke ofthe ram 14. The check valve part 150 of the foot valve 48 is springloaded by spring 152 and opens on downward movement of the piston 154 incylinder 20 on the downward stroke of the ram 14 sufficient to build apressure in chamber 144 overcoming spring 152. The spring 152 isprovided to prevent lowering of the ram 14 due to leakage of hydraulicfluid from cylinder 20 as the result of the weight of the ram 14 whenthe press 12 is left in an idle condition with the ram 14 up.

The over-all operation of the press 12 and hydraulic apparatus 10includes a complete downward stroke of the ram 14 for forming aworkpiece and a return stroke of the ram 14 into its upper position, asshown in FIG- URE 1, ready for a subsequent downward stroke. Thus, thecycle of the press 12 and hydraulic apparatus 10 starts with the ram 14in an upper position, as shown in FIGURE 1.

With the ram 14 in the upper position and the manual four-way valve 34unactuated the piston 98 of the hydraulic transformer 16 will be in itsfully down position so that the chamber 106 will be filled withhydraulic fluid and the recess 100 will be empty. The. piloted four-wayvalve 38 will be positioned, as shown in FIG- URE 2, to provide a fluidpath between conduits 108 and 110 for communication between the chamber106 of hydraulic transformer 16 and chamber 112 of cylinder 20.

The manual four-way valve 34 is moved to the left in FIGURE 2 to connectthe pump 18 through conduits 58, 68, 78, 80 and 82 to the hydraulictransformer 16 through the check valve portion 76 of the sequencingvalve 36. Hydraulic fluid under pump pressure of, for example, onethousand pounds per square inch will therefor flow into the chamber 100of the hydraulic transformer 16 at a rate of, for example, fifteengallons per minute. The piston 98 of the hydraulic transformer 16 ismoved upward so that hydraulic fluid is forced out of chamber 106 ofhydraulic transformer 16 at a pressure of two hundred fifty pounds persquare inch at a rate of sixty gallons per minute through conduits 108and 110 into the chamber 112 of cylinder 20. The piston 154 and thus theram 14 of the press 12 connected thereto is therefore moved down rapidlyto approach a workpiece (not shown) which may be on the bed 24 of thepress 12.

On the downward movement of the ram 14 the piston 154 forces thehydraulic fluid from the chamber 144 through conduit 146, the springloaded check valve part 150 of foot valve 48, conduit 70, four-way valve34 and conduit 74 to tank 28.

As the ram 14 approaches the workpiece the cam 126 carried by the ram 14will actuate the four-way switching valve 40 to connect the pilot lines116 and 114, whereby the piloted four-way valve 38 is moved to the leftin FIG- URE 2 to block the conduit 108 and connect the conduits 84 and110. The hydraulic fluid passed from the sump 18 through conduit 68 andsequencing valve 36 will now pass directly through conduits 78, 84 and110 into the chamber 112 of cylinder 20 at a pressure of one thousandpounds per square inch at a pump rate of fifteen gallons per minute. Theremainder of the stroke of the ram 14 during which a workpiece isengaged and work such as trimming performed thereon is carried out at alower speed under higher pressure.

On subsequent actuation of the four-way valve 34 to the right in FIGURE2 the hydraulic fluid from pump 18 is pumped .into the chamber 144 ofcylinder 20 to raise the ram 14 through conduit 70, the check valveportion 148 of foot valve 48 and conduit 146. Raising of the piston 154in cylinder 20 causes the hydraulic fluid in the upper part 112 ofcylinder 20 to be discharged therefrom through conduit 110 back throughconduit 108, back into chamber 106 of the hydraulic transformer 16through the piloted four-way valve 38 which has been returned to theright due to a pilot signal from the pilot conduit 72 which is connectedto the conduit 70.

The hydraulic fluid in the chamber 106 will bottom the piston 98 on therod 94 since the cylinder 20 has a greater capacity in the upper chamber112 than the capacity of chamber 106. The capacity of chamber 106 isslightly greater than the capacity of chamber 112 with the ram inposition to actuate valve 40. The excess hydraulic fluid pumped intochamber 106 will cause actuation of the pressure relief valve 52 and theexcess hydraulic fluid will be passed from the chamber 106 back to thehydraulic fluid tank 28 through conduit 140, pressure relief valve 52,conduit 142, conduit 68, four-way valve 34 and conduit 74.

The hydraulic fluid will be returned to the chamber 106 at approximatelypump pressure of one thousand pounds per square inch and at a rate offifteen gallons per minute. The fluid will however be forced out ofrecess at approximately four thousand pounds per square inch and at arate of three and one-fourth gallons per minute. The hydraulic fluidforced out of the recess 100 will be returned to the pump side of thefour-way valve 34 through check valve 50.

If due to knock-out or stripper structure connected to the press ram 14operable on the return stroke of the press ram the pressure in theconduit 58 exceeds that in the conduit 82 so that return of hydraulicfluid from the hydraulic transformer through check valve 50- is notpossible, the additional pressure in conduit 78 will actuate thepressure relief valve portion 86 of the sequencing valve 36 to returnthe hydraulic fluid from the hydraulic transformer 16 through theconduit 68 to the hydraulic fluid tank 22 through four-way valve 34 andconduit 74.

As the ram 14 proceeds upwardly, the cam 136 will actuate the four-wayram upper limit valve 44 to connect the pilot lines 128 and 130, wherebythe bypass valve 54 is actuated to cause bypassing of the hydraulicfluid from the pump 18 back to the hydraulic fluid supply tank 28through conduits 62 and 138. The effective height of the return strokeof the ram 14 is thus limited by the height of the cam 136.

Thus, it is seen that there is provided hydraulic actuating apparatusfor a press capable of moving the ram toward a workpiece at a fastspeed, as, for example, six hundred inches per minute at a relativelylow pressure 'and subsequently moving the ram toward the workpiece at aslower speed at 'a much higher pressure which hydraulic apparatusincludes a single pump operating at a single speed in contrast to theprior more complicated hydraulic apparatus for performing a similarfunction including 'a plurality of pumps or motors and/ or variablepumps and motors and complicated connections therefor which have beenmore expensive and less eflicient than the hydraulic apparatus disclosedincluding a single motor and a hydraulic transformer.

While one embodiment of the present invention has been considered indetail, it will be understood that other embodiments and modificationsthereof are contemplated. It is the intention to include all embodimentsand modifications as are defined by the appended claims within the scopeof the invention.

What I claim as my invention is:

1. Hydraulic actuating apparatus for a hydraulic press including a pressram and a ram piston and ram cylinder for moving the press ram, saidactuating apparatus comprising a source of hydraulic fluid, a pumpconnected to the source of hydraulic fluid, a motor connected to drivethe pump to provide hydraulic fluid at the output thereof at a highpressure and low rate, a hydraulic transformer connected between thepump and ram cylinder operable to receive hydraulic fluid from the pumpat the high pressure and low rate and to supply hydraulic fluid to theram cylinder at a high rate and low pressure in response thereto, meansresponsive to the position of the ram for bypassing hydraulic fluid fromthe pump around the hydraulic transformer and directly to the ramcylinder and hydraulic means for returning the ram to a predeterminedposition including a piloted pump bypass valve and pilot valve meansoperable in response to the position of the press ram for actuating thepiloted pump bypass valve to limit the return movement of the ram.

2. Apparatus as set forth in claim 1 wherein the means for bypassing thehydraulic fluid around the hydraulic transformer comprises a pilotedvalve for effecting the hydraulic fluid bypass on actuation thereof, aswitching valve operable on actuation to provide a pilot signal to thepilot valve for actuation thereof and cam and cam follower mechanismoperable between the press ram and switching valve for actuation of theswitching valve in response to a predetermined position of the ram.

3. Apparatus as set forth in claim 1 wherein the hydraulic transformeris recharged on the return stroke of the press ram and wherein the ramcylinder has a larger capacity than the hydraulic transformer and meansconnected to the hydraulic transformer for bypassing excess hydraulicfluid back to the hydraulic fluid source on the return stroke of the ramafter the hydraulic transformer is recharged.

4. Apparatus as set forth in claim 1 and further including a foot valvein series between the ram cylinder and pump for permitting substantiallyunrestricted pumping of high pressure fluid into the ram cylinder duringthe return stroke of the ram and for permitting biased return ofhydraulic fluid in the ram cylinder to the source of hydraulic fluidduring the work forming stroke of the ram to prevent movement of the ramin a work forming direction due to the weight thereof.

5. Hydraulic actuating apparatus for a hydraulic press including a ramand a hydraulic cylinder and piston for actuating the ram in workforming and return str'okes comprising a source of hydraulic fluid, apump connected to the source of hydraulic fluid, a motor connected tothe pump for driving the pump to provide a hydraulic output therefrom ata predetermined pressure and a predetermined rate, a four-way actuatingvalve in the pump output line and a sequencing valve in series, ahydraulic transformer for receiving hydraulic fluid at the predeterminedpressure and rate from the sequencing valve and providing hydraulicfluid at a lower pressure and higher rate in response thereto to the ramcylinder connected to receive the output of the sequencing valve, apiloted valve connected to the sequencing valve, hydraulic transformerand ram cylinder for bypassing the hydraulic signal at the predeterminedpressure and rate from the pump around the hydraulic transformer anddirectly to the ram actuating cylinder on actuation there- .up-stroke ofthe ram.

of, a four-wayswitching valve operable on actuation to actuate thepiloted four-way valve and-means resp'onsive to the ram position foractuating the switching valve to bypass the hydraulic fluid from thepump directly to the ram actuating valve through the sequencing valveand piloted valve whereby initial movement of the press ram during awork forming stroke is at a high speed under a low pressure andsubsequent movement of the ram in the work forming stroke is at a lowspeed under a high pressure.

6. Apparatus as set forth in claim 5 and further including a connectionbetween the manual four-way valve and the ram cylinder for providinghydraulic fluid to the ram cylinder during the return stroke of theramand further including a foot valve connected. between the manualfour-way valve and ram cylinder for preventing Work forming movement ofthe ram due to the weight of the ram.

7. Apparatus as set forth in claim 5 wherein the ram cylinder is ofgreater capacity than the hydraulic transformer whereby the hydraulictransformer is fully charged on the return stroke of the ram and apressure relief valve connected between the hydraulic transformer andthe source of hydraulic fluid during the return stroke of the ram.

8. Apparatus as set forth in claim 5 and further including a pilotedpump bypass valve for bypassing hydraulic fluid around the pump onactuation thereof, a pilot valve for actuating the piloted pump bypassvalve in response to actuation thereof and means operably associatedwith the ram for actuating the pilot valve on the ram reaching an upperlimit in its return stroke.

9. Apparatus as set forth in claim 5 and further including a sequencevalve between the pump and hydraulic transformer including a pilotedpressure relief portion for returning the hydraulic fluid from the highpressure side of the hydraulic transformer during the up-stroke of a ramin response to knock-out structure operable on the 10. Apparatus as setforth in claim 5 wherein the hydraulic transformer comprises a pair ofend plates, a cylinder extending between the pair of end plates andmeans within the cylinder for providing a high volume, low pressureoutput from one end of the cylinder in response to a high pressure, lowvolume input to the other end of the cylinder.

11. Apparatus as set forth in claim 10 wherein the means within thecylinder comprises a rod having an opening extending therethroughconnected to one of the end plates at one end of the cylinder forreceiving the high pressure, low volume signal therethrough and a pistonwithin the cylinder having a recess in one end thereof into which therod is inserted.

12. Apparatus as set forth in claim 5 and further including a connectionbetween the manual four-way valve and the ram cylinder for providinghydraulic fluid to the ram cylinder during the return stroke of the ram.

13. Apparatus as set forth in claim 5 and further including a foot valveconnected between the manual four-Way valve and ram cylinder forpreventing work forming movement of the ram clue to the weight of theram.

14. Hydraulic actuating apparatus for a hydraulic press including apress ram and a ram piston and ram cylinder for moving the press ram,said actuating apparatus comprising a source of hydraulic fluid, a pumpconnected to the source of hydraulic fluid, a motor con nected to drivethe pump to provide hydraulic fluid at the output thereof at a highpressure and low rate, a hydraulic transformer connected between thepump and ram cylinder operable to receive hydraulic fluid from the pumpat the high pressure and low rate and to supply hydraulic fluid to theram cylinder at a high rate and low pressure in response thereto, meansresponsive to the position of the ram for bypassing hydraulic fluid fromthe pump around the hydraulic transformer and directly to the ramcylinder and a check valve between the hydraulic transformer and thepump for returning hydraulic fluid to the pump on the return stroke ofthe press ram and a piloted pressure relief valve between the hydraulictransformer and the source of hydraulic fluid for providing an alternatedischarge path for the fluid in the hydraulic transformer during thereturn stroke of the press ram.

15. Hydraulic actuating apparatus for a hydraulic press including apress ram and a ram piston and ram cylinder for moving the press ram,said actuating apparatus comprising a source of hydraulic fluid, a pumpconnected to the source of hydraulic fluid, means for driving the pumpto provide hydraulic fluid at the output thereof at a high pressure andlow rate, means operable between the output of the pump and the pressram for feeding hydraulic fluid into the ram cylinder at -a high rateand low pressure in response to operation of said pump during an initialportion of the work forming stroke of the ram and for feeding hydraulicfluid at the pump pressure and rate into the ram cylinder during theremainder of the ram work forming stroke and a check valve between thelast mentioned means and the pump for returning hydraulic fluid to thepump on the return stroke of the press ram and a piloted pressure reliefvalve between the last mentioned means and the source of hydraulic fluidfor providing an alternate discharge path for the fluid in the lastmentioned means during the return stroke of the press ram.

16. Hydraulic actuating apparatus for a hydraulic press including apress ram and a ram piston and ram cylinder for moving the press ram,said actuating apparatus comprising a source of hydraulic fluid, a pumpconnected to the source of hydraulic fluid, means for driving the pumpto provide hydraulic fluid at the output thereof at a high pressure andlow rate, means operable between the output of the pump and the pressram for feeding hydraulic fluid into the ram cylinder at a high rate andlow pressure in response to operation of said pump during an initialportion of the work [forming stroke of the ram and for feeding hydraulicfluid at the pump pressure and rate into the ram cylinder during theremainder of the ram work forming stroke, and hydraulic means forreturning the ram to a predetermined position including a piloted pumpbypass'valve and pilot valve means operable in response to the positionof the press ram Er actuating the piloted pump bypass valve to limit thereturn movement of the ram.

References Cited by the Examiner UNITED STATES PATENTS 1,256,451 2/ 1918Ensign et al 6054.5 2,183,983 12/1939 Bostwick 6052 2,253,617 8/1941Griflith 60-52 2,408,513 10/ 1946 Gunderson 6054.6

EDGAR W. GEOGHEGAN, Primary Examiner.

1. HYDRAULIC ACTUATING APPARATUS FOR A HYDRAULIC PRESS INCLUDING A PRESSRAM AND A RAM PISTON AND RAM CYLINDER FOR MOVING THE PRESS RAM, SAIDACTUATING APPARATUS COMPRISING A SOURCE OF HYDRAULIC FLUID, A PUMPCONNECTED TO THE SOURCE OF HYDRAULIC FLUID, A MOTOR CONNECTED TO DRIVETHE PUMP TO PROVIDE HYDRAULIC FLUID AT THE OUTPUT THEREOF AT A HIGHPRESSURE AND LOW RATE, A HYDRAULIC TRANSFORMER CONNECTED BETWEEN THEPUMP AND RAM CYLINDER OPERABLE TO RECEIVE HYDRAULIC FLUID FROM THE PUMPAT THE HIGH PRESSURE AND LOWER RATE AND TO SUPPLY HYDRAULIC FLUID TO THERAM CYLINDER AT A HIGH RATE AND LOW PRESSURE IN RESPONSE THERETO, MEANSRESPONSIVE TO THE POSITION OF THE RAM FOR BYPASSING HYDRAULIC FLUID FROMTHE PUMP AROUND FOR BYPASSING TRANSFORMER AND DIRECTLY TO THE RAMCYLINDER AND HYDRAULIC MEANS FOR RETURNING THE RAM TO A PREDETERMINEDPOSITION INCLUDING A PILOTED PUMP BYPASS VALVE AND PILOT VALVE MEANSOPERABLE IN RESPONSE TO THE POSITION OF THE PRESS RAM FOR ACTUATING THEPILOTED PUMP BYPASS TO LIMIT THE RETURN MOVEMENT OF THE RAM.